Storage media having a wide servo band and high data format efficiency and a storage using the same

ABSTRACT

A servo control method for a storage media includes arranging a plurality of servo sectors along a circumferential direction of the disk-type storage medium without successively arranging the plurality of servo sectors in a radial direction and arranging a plurality of data sectors which are not split by the servo sectors.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 09/572,402 filed May16, 2000, now U.S. Pat. No. 6,469,853, the subject matter of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to a servo format and a data format for amagnetic disk and a magnetic disk device having a wide tracking servoband and high head positioning performance.

FIG. 4 shows an example of constitution of a magnetic disk device (HDD)100. HDD 100 includes a head disk assembly (HDA) 200 including amagnetic disk 2, a magnetic head 1, a carriage 3, a read/writeintegrated circuit (R/W IC) 4 attached onto carriage 3, and a motor 5and a package board (PCB) 300 including a read channel 31, a hard diskcontroller chip (HDC) 32, a servo control circuit (SC) 33, amicroprocessor (MP) 34, a read-only memory (ROM) 36, and a random accessmemory (RAM) 37.

HDD 100 incorporated in a redundant arrays of independent disk (RAID)system or the like needs, in addition to a high-speed transfer rate anda large capacity, strength against external disturbance such asvibration for the following reasons. Many drives (HDDs) are disposed ina housing of the RAID system and operate at the same time and hencecause vibration stronger than that caused by operation of a single HDD.Therefore, to endure the environment, it is required to employ apositioning system which is strong again external disturbance ofvibration.

FIG. 5 shows a layout of a servo area 27 and a data area 28 on magneticdisk 2. The areas are subdivided into a plurality of data zones 29 in adirection from an inner circumference to an outer circumference, andeach zone has a data transfer rate. In this situation, to dispose apositioning system which is strong against external disturbanceprimarily of vibration, it is necessary to decrease the servo sampleperiod and to improve the servo control band. A wide tracking servo bandis guaranteed by increasing the number of servo sectors per diskcircumference as shown in FIG. 12, which will be described later. FIG. 5shows an example of construction in which the number of servo sectors is32.

In a 3.5 inch HDD of 7200 rotations per minute (rpm) to 10000 rpm forthe recent RAID system, the number of servo areas 27 can be increasedand the servo sample period is reduced by minimizing the length of eachservo area 27 per disk. In other words, this is because the physicallength of the servo area can be reduced to about one half of theoriginal length by changing the burst cycle frequency to a high value,i.e., from 20 MHz to 40 MHz as shown in FIG. 12, which will be describedlater.

This can be achieved primarily by a signal of a higher frequency (to bereferred to as a servo frequency herebelow) for one bit of a servosignal (corresponding to one cycle of a signal in a position errorsignal (PES)). In the past several years, the servo frequency of the HDDfor RAID has rapidly increased from about 10 MHz to a range from about20 MHz to about 30 MHz, and the number of servo areas per circumferenceof a magnetic disk has increased from about 50/circumference to about100/circumference. This has improved the servo band from about 400 Hz toabout 800 Hz.

The total length of servo areas 27 in the circumferential directionlittle changes since the increase in the servo frequency is nearly ofthe same magnitude as that in the number of servo areas. Consequently,the ratio of allocation of data area 28 is kept unchanged. However, asshown in FIG. 6, as the number of servo areas increases, the chance inwhich a data sector is split (to be referred to as a split sector 25) indata area 28 becomes greater. This increases additional areas (shadeareas in FIG. 6) such as AGC (automatic gain control (AGC)/phase lockedloop (PLL) acquisition area) 17 of the data sector, and hence the dataformatting efficiency is reduced.

FIG. 6 shows in its upper section a reproduced waveform 6 of a servosector of a full format (the servo sector in this case is a zonecorresponding to each servo area 27 drawn with a bold line in the radialdirection in FIG. 5). Full-format servo sector 6 includes an AGC/PLLacquisition area (AGC/PLL) 7, a servo address mark area (AM) 8, a servosector address area (SSA) 9-1, a track ID area (TID) 9-2, and positionerror signal areas (PESA to PESD) 10 to 13. This configuration includesPESA to PESD, for example, a signal of a fixed frequency is recorded atdifferent positions in the tracking direction for A to D. Even two kindsthereof such as A and B can achieve the tracking control function.

These areas are arranged on magnetic disk 2 in its circumferentialdirection with an equal interval therebetween. The areas arediscriminated from data to be demodulated according to a servo gate(SGATE) 14. Data sectors 25 and 26 are formatted in areas other thanservo area 27. If the interval of SGATE 14 is sufficiently large, only afew data sectors are divided by a servo area at an intermediate pointthereof as can be seen from a non-split sector 26, and hence no problemoccurs. However, when the interval of SGATE 14 becomes smaller, thenumber of split sectors 25 divided by a servo area at an intermediatepoint thereof increases.

Non-split sector 26 includes fields of time (ISG1/2) 16 and 22 necessaryfor the rise and fall time of a read/write circuit system or the likeand for absorption of fluctuation in rotation of magnetic disk 2, AGC 17necessary to acquire AGC/PLL, SYNC 18 indicating a start point of data,encoded data (DATA), a cyclic check code (CRC) 23, an error correctioncode (ECC) 24, and PAD 21 necessary to determine data and to absorb aread delay of a read/write channel. However, since split sector 25 needsISG1/2, AGC, SYNC, and PAD in duplication as indicated by shades, dataarea 28 is reduced.

One solution of this problem is to increase the servo frequency of servoarea 27. Namely, by minimizing the physical length of the servo area,data area 28 itself is further enlarged. This idea is implemented in amethod which, as disclosed in U.S. Pat. No. 5,784,219 (as shown in FIG.7), employs a mixed configuration of servo sectors of full format 6 andshort format 6-1. Short-format servo sector 6-1 is disposed betweenfull-format servo sectors 6 to remove from short-format sector 6-1 theAGC/PLL, AM, SSA, and TID fields of the full format, namely, only PES isused. Since full-format servo sector 6 and short-format sector 6-1appear alternately, the difference in format can be discriminated. Theprior art shown in FIG. 7 as a configuration of the alternatingarrangement of the full format and the short format of servo sectors.However, consideration has not been given at all to a relationshipbetween this arrangement and the data split.

FIG. 10 shows a configuration example of servo sectors of the prior art.Full-format servo sector 6 of FIG. 6 includes AGC/PLL, AM, SSA, TID, andPESA to PESD respectively having lengths of 40, 8, 8, 16, and 12×4cycles, and hence the total length is 120 cycles as shown in FIG. 10.Short-format servo sector 6-1 includes PESA to PESD each having a lengthof 16.5×4 cycles and the total length is 66 cycles. The PES length iselongated (from 12 cycles to 16.5 cycles) in consideration offluctuation in the disk rotation and the like. The gain of AGC acquiredin the preceding full format area is used for short format 6-1. Sincesynchronization of PLL is not required to demodulate PES of short format6-1, AGC/PLL area 7 can be dispensed with.

By opening SGATE 14-1 for the short format using as a mark the AMposition detected in the preceding full format area, SSA 9-1 and TID 9-2can also be deleted for the short format 6-1. In this operation, onlyfull-format servo sector 6 is decoded in the seek operation of the head,and short-format servo sector 6-1 is demodulated only in the followingoperation (in a state in which the head position is held at apredetermined track position). All of four PES information items of PESAto PESD of short format 6-1 are not necessary, and it is assumed thateven two information items, i.e., PESA and PESB can cope with theoperation in principle.

FIG. 11 shows formats of data sectors 25 and 26 in this case. Non-splitsector 26 not split by a servo sector is 625 byte long, and split sector25 split by a servo sector into a front field 25-1 and a back field 25-2and has a total length of 690 bytes.

For the servo/data formats of FIGS. 10 and 11, the data area ratio(format efficiency) of a 10000 rpm HDD is calculated by changing thenumber of servo sectors and the burst cycle frequency (servo frequency).The data transfer rate is kept fixed as 30 MB/s. FIG. 12 shows resultsof the calculation.

The results of calculation of FIG. 12 are grounded as follows. Datasectors can be allocated to an area obtained by subtracting the servoarea from an area corresponding to six milliseconds (msec) of onecircumference. The number of non-split sectors can be calculated bysubtracting the total split data sector length from the area. This leadsto the total number of data sectors on the circumference of the magneticdisk. The data area ratio is calculated as a ratio of the area lengthdetermined by “512-byte long user data×total number of data sectors” tothe length in the circumferential direction. The ratio of AGC or thelike is calculated as a ratio of 65×2=130 bytes for a split sector and65 bytes for a non-split sector to the length in the circumferentialdirection. The ratio of ECC or the like is calculated as a ratio of“total number of data sectors×48 bytes” to the length in thecircumferential direction.

In FIG. 12, Type A is an HDD having a relatively narrow servo band inwhich the servo frequency is 20 MHz when the number of servo sectors is80. It is assumed in this case that the number of split data sectors is40 corresponding to about 50% of the number of servo sectors. Since thetotal number of data sectors is 260, the format efficiency (data arearatio) can be calculated as about 73.9%.

Type B1 is an HDD with an increased servo band with the servo area ratiokept unchanged. The number of servo sectors is increased to 160 and theservo frequency is increased to 40 MHz. Since the number of servosectors is 160 and type A has 260 sectors, it is assumed that the numberof split data sectors in this case is increased to 120 which is about75% of the servo sectors. The increase in the split data sectors causesthe area ratio of AGC or the like to be increased by 2.6 points from10.8% to 13.4%. Therefore, the format efficiency (data area ratio) isdecreased by 2.3 point to about 71.6%.

Type B2 shows a case of an application of U.S. Pat. No. 5,784,219 inwhich 50% of the 160 servo sectors of Type B are short-format servosectors. Since the servo area ratio is improved by 1.8 points from 8% to6.2%, the format efficiency is improved by about 1.5 points to about73.1%. However, when compared with Type A of a narrow servo band (with asmaller number of servo sectors per disk circumference), the lowering ofthe format efficiency cannot be avoided.

As above, although a little improvement can be attained by combiningshort-format servo sectors of the prior art, the increase in the ratioof AGC or the like caused by the split data sectors is large as 2.6points to 2.8 points. Therefore, it is unavoidable that the formatefficiency is lowered by the increase in the servo band

SUMMARY OF THE INVENTION

To solve the problem above, the present invention primarily adoptsconstitution as follows.

In a magnetic disk including a plurality of servo sectors and datasectors which are divided along a circumferential direction, there areincluded servo sectors of a full format which are successively arrangedin a radial direction of a magnetic disk and which include trackinformation and servo sectors of a short format which are arrangedbetween the full-format servo sectors, which are not successivelyarranged in a radial direction of the magnetic disk, and which includeposition error signals. The servo sector of the short format does notsplit a data sector.

In the magnetic disk, the short-format server sectors include aplurality of servo formats having different recording lengths.

The magnetic disk includes a gap of at least one track between datazones obtained by dividing an area of the magnetic disk from an innercircumference to an outer circumference thereof.

In a magnetic disk including a plurality of servo sectors and datasectors which are divided along a circumferential direction, a disk areais subdivided in a direction from an inner circumference to an outercircumference of the magnetic disk into a plurality of data zones eachhaving one data transfer rate. There are disposed servo sectors of afull format which are successively arranged in a radial direction of amagnetic disk and which include track information and servo sectors of ashort format which are arranged between the full-format servo sectorsand which include position error signals. The servo sectors of the shortformat are not successively arranged in the radial direction betweenadjacent data zones.

In a magnetic disk device including a head disk assembly, a read/writechannel, a hard disk controller, a servo control section, and amicroprocessor, only full-format servo sectors which are successivelyarranged in a radial direction of the magnetic disk and which includetrack information are decoded during a seek operation and short-formatservo sectors which are arranged between the full-format servo sectors,which are not successively arranged in a radial direction of themagnetic disk, and which include position error signals are demodulatedduring a following operation.

Full-format servo sectors which include track information are recordedto be successively arranged in a radial direction of a magnetic disk andshort-format servo sectors including position error signals are recordedbetween the full-format servo sectors not to be successively arranged ina radial direction of the magnetic disk.

In a magnetic disk device including a head disk assembly, a read/writechannel, a hard disk controller, a servo control section, and amicroprocessor, there are included a signal processing circuit whichdecodes servo sectors of a full format which are successively arrangedin a radial direction of a magnetic disk and which include trackinformation which includes one input of a servo control signalindicating a servo sector. The signal processing circuit includesfull-format sector detecting means for detecting from the full-formatservo sector that the sector is a servo sector of full format and areacreating means for constructing an area to detect from a result of thedetection of the full-format servo sector a short-format servo sectorincluding position error signals. A servo control signal inputted duringan output operation of the area creating means is recognized as anindication of a short-format servo sector.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become moreapparent from the consideration of the following detailed descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagram showing a layout of an embodiment of a magnetic diskin accordance with the present invention;

FIG. 2 is a block diagram showing an embodiment of a servo decodercircuit system in accordance with the present invention;

FIG. 3 is a diagram showing another example of constitution of a shortformat of servo sectors in the embodiment;

FIG. 4 is a schematic diagram showing a configuration of a magnetic diskdevice of the prior art;

FIG. 5 is a diagram showing a layout of a magnetic disk format of theprior art;

FIG. 6 is a diagram showing details of a servo format and a data formatof the prior art;

FIG. 7 is a diagram showing details of a short format of servo sectorsof the prior art;

FIG. 8 is a diagram for explaining a method of recognizing ashort-format servo sector in the embodiment of the present invention;

FIG. 9 is a diagram for explaining improvement of the format efficiencywhen the present invention is applied;

FIG. 10 is a diagram showing the length of the servo sectorconfiguration;

FIG. 11 is a diagram showing the length of the data sectorconfiguration; and

FIG. 12 is a diagram for explaining a state of the format efficiency inaccordance with the prior art.

DESCRIPTION OF THE EMBODIMENTS

Referring mainly FIGS. 1, 2, 3, 8, and 9, description will be now givenof a technique regarding a servo format and a data format which have awider servo band and high data format efficiency in accordance withembodiments of the present invention.

FIG. 1 shows servo and data formats in accordance with an embodiment ofthe present invention. The formats include full-format servo areas 27successively arranged in a radial direction of a magnetic disk 2 andshort-format servo areas 6-1 separated by a data zone in a radialdirection. Servo sectors of full format 6 and short format 6-1 have thesame detailed configuration as shown in FIGS. 6 and 7 described inconduction with the prior art.

Although FIG. 1 includes eight full-format servo sectors in acircumference and five data zones in a radial direction forsimplification of explanation, there are actually included 80full-format servo sectors in a circumference and 16 data zones in aradial direction.

Additionally, although full-format servo sectors 6 exist along a radialline from a center of magnetic disk 2 in the diagram, these sectors areactually arranged in a contour of an arc in a radial direction to tracea locus of a head in a head seek operation.

In this embodiment, each of the data zones 29-1 to 29-5 is allocatedsuch that a data sector may be split by full-format servo sector 6, butis not split by short-format servo sector 6-1. Therefore, betweenadjacent data zones having different data transfer rates, short-formatservo sector 6-1 is different in position and is not successive (isseparated) at a boundary of data zone 29. In consequence, a gap of atleast one track is disposed between data zones to avoid interferencebetween short servo sector 6-1 and data sectors 25 and 26 betweenadjacent zones.

FIG. 2 shows a mechanical section concerning magnetic disk 2 andcarriage 3 and mainly the configuration of a circuit board (PCB) 300.Referring to this diagram, description will be given of a servodemodulating operation and a method of recording servo sectors of shortformat 6-1. In FIG. 2, various circuits assigned with a branch number tocode 33 designate specific units of servo control circuit 33 shown inFIG. 4.

When magnetic disk 2 rotates and a position of full servo sector 6approaches, a preamplifier 4 of R/W IC 4 amplifies this signalindicating the condition and outputs the signal to a read channel. Readchannel 31 is then set to a servo decoding mode by SGATE 14-1 issuedfrom a hard disk controller (HDC) 32. In a code data string 31-1outputted from read channel, a servo mark/code detector circuit 33-1detects an address mark, a servo sector mark, a gray code, etc. Onreceiving a result of the detection, a servo controller 33-3 controls aposition control driver 33-5 to output a full-format servo sector markSSP to HDC 32 and a motor control driver 33-4.

Servo controller 33-3 also outputs a control signal Sgate for the PESdecoding operation to a servo PES demodulator 33-2. Servo PESdemodulator 33-2 demodulates, using an AM detection signal from servomark/code detector circuit 33-1 and SGATE signal 14-1, PESA to PESD froma sample value string 31-2 outputted from read channel 31 and outputs aresult of the decoding to servo controller 33-3. Servo controller 33-3is controlled by information in an ROM (36) and an RAM (37) in whichvarious area lengths and position information are recorded and which areconnected to a microprocessor 34.

A motor controller driver 33-4 controls a rotational speed of a magneticdisk 2. This control operation uses a full-format servo sector mark sspand a clock sclk of a servo frequency oscillator 33-6. In thisoperation, information of an interval between full-format servo sectorsrecorded on ROM (36) is used such that a period of time associated withthe count of clock sclk of servo frequency oscillator 33-6 is controlledto match the servo sector interval. The control operation may beconducted at an interval of a plurality of servo sectors.

In the head seek operation in a radial direction of magnetic disk 2,only full-format servo sectors 6 are used. This is achieved by servocontroller 33-3 under a control operation of position control driver33-5 in which controller 33-3 moves head 1 from a gray code recorded infull-format servo sector 6 to an objective track ID 9-2 while detectingtrack ID (TID) 9-2. Since short-format servo sector 6-1 does not includetrack ID 9-2, servo sector 6-1 is not demodulated in the seek operation.In this situation, information of the interval between full-format servosectors recorded on ROM (36) and information of each area length offull-format servo sector 6 are used to detect track ID 9-2. The rotationof magnetic disk and the seek control of head 1 above are almost thesame as those of the control technique of the prior art.

The embodiment of the present invention particularly conducts thefollowing control of head 1. When a following operation is indicated bymicroprocessor 34, servo controller 33-3 opens Sgate at a position ofshort format 6 according to information of each area length ofshort-format servo sector 6-1 stored in RAM (37), an AM position(address mark position) which can be detected in full-format servosector 6, servo sector address 9-1, and a data zone position. Thissignal sets read channel 31 to a servo modulation mode and initiatesservo PES demodulator 33-2, and PES information is also demodulated fromthis area 6-1. Servo controller 33-3 can control position control driver33-5 in a wide band using the PES information from full and short servosectors 6 and 6-1.

In this situation, servo PES demodulator 33-2 and servo mark/codedetector circuit 33-1 are integrally included in read channel 31, forexample, in a chip form. In this case, one signal (only SGATE) indicatesa servo area to discriminate a full-format servo area from ashort-format servo area, and two signals SGATE and Sgate are notinputted from servo controller 33-3.

FIG. 8 shows timing of signals to apply the present invention to thisconfiguration. That is, using the prior art, a Window 40 is configuredto detect servo sector pulse ssp in full-format servo sector 6 so as todetect a short-format servo sector according to the ssp. Inconsideration of fluctuation in the disk rotation, Window 40 is set tobe closed in any situation by when SGATE indicating the next full formatrises. This configuration recognizes SGATE inputted during this Windowas a short-format servo sector.

To arrange at arbitrary positions between the full-format servo sectorsan arbitrary number of short-format servo sectors including only PESsignals by a read channel which integrally includes servo PESdemodulator 33-2 and servo mark/code detector circuit 33-1 and whichincludes one SGATE input, it is required to adopt the read channelhaving a unit to discriminate the short format as above. Naturally, byapplying the read channel, it is possible to configure short-formatservo sectors between the full-format servo sectors.

Short-format servo sector 6-1 is demodulated basically only during thefollowing operation. Therefore, the four servo burst (PESA to PESD) isnot necessarily required as shown in FIG. 7, and the operation can beachieved also with the two servo burst.

This embodiment can cope with not only a format of a fixed data sectorlength but also a change in the data sector length. In the formatting ofdata sectors, it is possible to format short-format servo sectors 6-1.This can be achieved such that only full-format servo sectors 6 arerecorded by a servo formatting unit such as a servo writer and thenshort-format servo sectors 6-1 are recorded through an offset followingoperation in a direction of track width using information of full-formatservo sectors 6.

The operation will be concretely described using FIG. 2. First,according to the contents of the data sector format in ROM (36),microprocessor 34 calculates an Sgate position and positions of PESA toPESD for each data zone/servo sector address and stores the contentsresultant from the calculation in RAM (37). According to theinformation, head 1 is moved to an off-track position and PES writer 38is initiated only at the Sgate position to record a servo patterncorresponding to the offset position. The system repeatedly executesthis operation while conducting the off-track operation to therebyrecord the servo pattern of each PES. In the operation, if head 1 is ofa read/write separation type, the offset amount in the track directionneeds correction due to displacement of the gap position and the yawangle.

Ordinarily, short-format servo sectors 6-1 are arranged such that a datasector is not split thereby and data sectors and also short format 6-1are recorded by a servo writer. Therefore, the servo format set at thispoint determines the data sector length. However, when the short formatrecording method above is employed, the data sector length can bechanged after the servo write operation.

FIG. 9 is a diagram to explain format improving effect of thisembodiment. According to the servo/data format of FIGS. 10 and 11, thedata area ratio (format efficiency) of a 10000 rpm HDD is calculated bychanging the number of servo sectors and the cycle frequency (servofrequency). The data transfer rate is 30 MB/s which is equal to thevalue in the description of the prior art above. Data sectors can beallocated to data area 28 obtained by subtracting the servo area ratiofrom an area equivalent 6 msec of one circumference. The number ofnon-split sectors can be calculated by subtracting the total split datasector length from the area to resultantly obtain the total number ofdata sectors on the circumference of the magnetic disk.

The data area ratio is calculated as a ratio of the area lengthdetermined by “512-byte long user data×total number of data sectors” tothe length in the circumferential direction. The ratio of AGC or thelike is calculated as a ratio of 65×2=130 bytes for a split sector and65 bytes for a non-split sector to the length in the circumferentialdirection. The ratio of ECC or the like is calculated as a ratio of“total number of data sectors×48 bytes” to the length in thecircumferential direction.

Detailed description of Type A, Type B1, and Type B2 is similar to thedescription of the prior art above. Type C includes 160 servo sectorsincluding 40 full-format servo sectors 6 necessary for the head 1 seekoperation and the like, and remaining 120 short-format servo sectors6-1. It is assumed in the full-format servo sectors 6 that 20 datasectors (50% of the total full-format servo sectors) are split. Inaccordance with this servo-data format, when compared with the case ofType B2, the servo area ratio and the ratio of AGC and the like arerespectively improved by 0.9 point from 6.2% to 5.3% and by 3.3 pointsfrom 13.6% to 10.3%. The data area ratio (format efficiency) is improvedby 2.3 points from 73.1% to 75.4%.

In accordance with this embodiment above, by using short-format servosectors 6-1 not to split data sectors, the servo area ratio is naturallyimproved, the ratio of AGC and the like associated with the splitting ofdata sectors can be remarkably improved, and the format efficiency canbe resultantly improved. The efficiency is improved even when comparedwith the narrow servo band of Type A and it can be understood that theservo band becomes higher and the format efficiency is improved byapplying the present invention.

Although the format shown in FIG. 7 according to the prior art isapplied to short-format servo sector 6-1 in the mode for carrying outthe present invention, PLL acquisition area 7-1 and address mark (AM′)8-1 may be disposed before the PES area. When the clock phase in readchannel 31 is determined in PLL area 7-1 to detect AM′ 8-1 to determineinternal gates of PESA 10 to PESD 13 according to AM′ 8-1, the gatetiming margin caused by fluctuation in the disk rotation or the like canbe considerably lowered and each areas of PESA 10 to PESD 13 can beminimized.

As can be understood from the embodiment, by using a configuration inwhich short-format servo sectors 6-1 do not split data sectors and thenumber of short-format servo sectors is equal to or more than one halfof the total number of servo sectors, it is possible to widen the servoband and to improve the format efficiency.

In addition, by applying a magnetic disk device in accordance with tothe present invention, there can be implemented a portable device whichuses vibration for its operation and which can cope with an environmentwith strong vibration and shock as well as a highly reliable data serverwhich operates without performance loss.

As above, the embodiment of the present invention includes the followingconfiguration to achieve functions and operations as follows.

First, in accordance with the present invention, the servo and dataformats of a magnetic disk device include servo sectors of a full formatsuccessively arranged in a radial direction of a magnetic disk (notarranged in one direct line), and a data sector is not split by theservo sector. This makes it possible to reduce additional areas causedby splitting data sectors and to improve data format efficiency.

Second, the servo and data formats of the first configuration include aservo format having a plurality of recording lengths. This can furtherreduces the servo areas.

Third, there are included servo sectors of a full format successivelyarranged in a radial direction of a magnetic disk and servo sectors of ashort format which interpolate those of the full format and which arenot successively arranged in a radial direction of the magnetic disk,and a data sector is not split at least by the servo sector of the shortformat.

Fourth, in a magnetic disk device having a servo format of the first tothird configurations, a gap of at least one track is disposed betweenzones arranged on the magnetic disk in a radial direction thereof. Thisprevents deterioration of servo burst information even when theshort-format servo sectors are not successively arranged in the radialdirection.

Fifth, in a magnetic disk device having a plurality of servo formats,short-format servo sectors are not successive between data zonesarranged on the magnetic disk in a radial direction thereof.

Sixth, during a seek operation between data tracks, only full-formatservo sectors successively arranged in a radial direction of a magneticdisk are decoded, and during a following operation, also short-formatservo sectors not successively arranged in a radial direction of themagnetic disk are demodulated. This facilitates sequence control in aseek operation between data tracks.

Seventh, there are included a unit for recording servo sectors of a fullformat successively arranged in a radial direction of a magnetic diskand a unit for recording complementary servo sectors according toinformation of the full format servo sectors recorded. This allows auser to insert short-format servo sectors in a user site according tothe full-format servo sectors formatted in a factory, and hence avariable data format can be handled.

Eighth, there are included servo sectors not successively arranged in aradial direction, and the servo sectors have a plurality of servoformats. This prevents all data sectors from being recorded in a splitstate, and hence format efficiency is further improved.

Ninth, a signal processing circuit of a magnetic disk device whichincludes a demodulating unit for track information and position errorsignals and which includes one input of a servo control signalindicating a servo area includes a full-format sector detecting unit fordetecting, from a full-format servo sector including track information,that the sector is a full-format servo sector and an area creating unitfor configuring an area to detect a short-format servo sector includingposition error signals according to a result of the detection of thefull-format sector detecting unit. The processing circuit recognizes aservo control signal inputted during the output operation of the areacreating unit as a short-format servo sector. This enables detection ofa short-format servo sector existing at an arbitrary position betweenthe full-format servo sectors, and hence the degree of freedom of thedevice format is increased.

Tenth, by the signal processing circuit of the ninth configuration, anarbitrary number of short-format servo sectors including position errorsignals are arranged at arbitrary positions between the full-formatservo sectors including track information. This makes it possible toimplement, by minimizing the lowing of format efficiency, a magneticdisk device having wide-band servo control.

In accordance with the present invention, there can be provided amagnetic disk device which has a wide tracking servo band and high headpositioning performance and which develops high data format efficiency.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by thoseembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

What is claimed is:
 1. A servo control method for a storage media,comprising the steps of: arranging a plurality of servo sectors along acircumferential direction of the disk-type storage medium withoutsuccessively arranging the plurality of servo sectors in a radialdirection; and arranging a plurality of data sectors which are not splitby the servo sectors.
 2. A servo control method in accordance with claim1, further comprising the steps of: not successively arranging aplurality of servo sectors arranged in the radial direction; andsuccessively arranging a plurality of servo sectors in the radialdirection.
 3. A servo control method in accordance with claim 2,wherein: the plurality of servo sectors not successively arranged in theradial direction include servo sectors of a short format which includeposition error signals; and the plurality of servo sectors successivelyarranged in the radial direction includes servo sectors of a full formatwhich include track information.
 4. A servo control method in accordancewith claim 3, wherein short-format servo signals are obtained from theshort-format servo sectors and full-format servo signals from thefull-format servo sectors, more than two of the short-format servosignals appearing next to the full-format servo signal.
 5. A servocontrol method in accordance with claim 3, further comprising the stepof arranging a plurality of short-format servo sectors between thefull-format servo sectors.
 6. A servo control method in accordance withclaim 3, wherein the short-format servo sectors include a plurality ofservo formats having different recording lengths.
 7. A servo controlmethod in accordance with claim 3, including providing a plurality ofdata zones configured by subdividing the storage media in a directionfrom an internal circumference of the disk to an outer circumferencethereof, each zone having one data transfer rate.
 8. A servo controlmethod in accordance with claim 1, further comprising the step ofproviding a gap of at least one track between data zones configured bysubdividing the disk-type storage media in a direction from an internalcircumference of the disk to an outer circumference thereof.
 9. A servocontrol method in accordance with claim 1, wherein the disk-type storagemedia is a magnetic disk.
 10. A servo control method for storage,comprising the steps of: providing a head disk assembly including adisk-type storage media having short-format servo sectors recordedthereon including position error signals and full-format servo sectorsrecorded thereon including track information, and data recorded thereon;providing a head which reads the servo sector from the disk-type storagemedia and which conducts input/output operations of the data to/from thedisk-type storage media; providing an integrated circuit (IC) fortransferring data between the head and the storage media; providing achannel for controlling input/output operations to/from the head diskassembly; providing a controller for setting a mode of the channel to aservo sector read mode or to a data input/output mode; providing a servocontroller for demodulating the servo sectors of formats recorded on thestorage media; and controlling the servo controller and the channel witha microprocessor so that only the full-format servo sectors are decodedduring a seek operation of the head and only the short-format servosectors are demodulated during a following operation of the head.
 11. Aservo control method in accordance with claim 10, wherein thefull-format servo sectors are decoded by detecting the trackinformation.
 12. A servo control method in accordance with claim 10,wherein the short-format servo sectors are demodulated by detecting aservo sector of the short format according to detection of a servosector pulse in the full-format servo sector.
 13. A servo control methodin accordance with claim 10, wherein more than two short-format servosignals appear next to the full-format servo signal.
 14. A servo controlmethod in accordance with claim 11, wherein more than two short-formatservo signals appear next to the full-format servo signal.
 15. A servocontrol method in accordance with claim 12, wherein more than twoshort-format servo signals appear next to the full-format servo signal.